Screw-cutting die



June 24, 1930. E, T, QYSSHEETAL 1,766,598

SCREW CUTTING DIE Filed Feb. 28, 1928 4 Sheets-Sheet Jung 24, 1 930. E. BYSSHE ET AL ,5

SCREW CUTTING DIE Filed Feb. 28, 1928 4 sheets sheet 2 lmnllluml-uunu :[1|'|ill L k? nnmnum A mzmmmm w ICTZTI'. w MI 26 A mm v I 47 e I a2 June 24, 1930. E. T. BYSSHE ET AL 1,766,598

SCREW CUTTING DIE Fi 1 2 4 Sheets-Sheet 3 June 24, 1930. E. 'r. BYssH L SCREW GUTTING DIE Filed Feb 28. 1928 4 Sheets-sheaf, 4

Patented June 24, 1930 UNHTED STATES PATENT ERNEST '1. BYSSHE AND ROBERT E. FINN, OF SPRINGFIELD, VERMONT, ASSIGNOB-S TO JONES & LAMSON IMACHINE COMPANY, OF SPRINGFIELD, VERMONT, A CORPORA- TION F VERMONT Application filed February 28, 1928.

This invention relates to a screw thread cutting die of a type which may be fixed in the turret of an automatic machine. It is an object of the invention to provide a die which is simple, compact, and rugged, and which is positively secured against prematureopening after it has been closed. The invention may be embodied in a die having relatively few parts, the die being provided with a positive lock against opening, the lock being arranged to be released by the operative engagement of work with the die. Various additional advantageous features of construction will be apparent to one skilled in the art from the disclosure of the invention in the following description and on the drawings, of which,

Figure 1 is a side elevation of a die embodying the invention.

Figure 2 is a plan view of the same. Figure 3 is a front end view of the same. Figure 4 is a longitudinal section on the line l-4t of Figures 2 and 3.

Figure 5 is a longitudinal section in a v different plane on the line 55 of Figure 1.

Figure 6 is a transverse section on the line 6-6 of Figures 2 and 4.

Figure 7 is an elevation of a latch pin. Figure 8 is a section on the line 88 of Figure 7 s Figure 9 is a section on the line 99 of Figure 7 Figure 10 is a section on the line 10-10 of Figure 5.

Figure 11 is a rear end elevation of the die.

Figure 12 is a perspective view of the body portion of the die.

Figure 13 is an elevation of a driving plate.

Figure 14 is a section on the line 1l1-1 of Figure 18.

Figure 15 is a front end elevation of the sleeve of the die, a portion being broken away.

Figure 16 is a side elevation of the same.

Figure 17 is a perspective view of the stationary shank of the die.

Briefly, the die illustrated on the drawings comprises a fixed shank, a body member,

50 the rear portion of which is supported in SCREW-CUTTING DIE Serial No. 257,638.

the shank, the forward portion of the body member having thread-cutting chasers mounted therein. A sleeve slides forwardly on the intermediate portion of the body member to force the chaser-s inwardly and thus to close the die for operation on work. The forward motion of the sleeve is effected by a simple rack and pinion device, and a latch is provided to engage the sleeve and hold it in its forward, die-closing position. If, when the die is closed, the body and sleeve be moved forward together as when pulled by the work, the latch is released and the sleeve springs back to open the die.

Referring to the drawings in detail, 20 represents a stationary shank which sup ports the other members of the die and is itself adapted to be clamped in fixed position in a lathe or the turret of an automatic machine. The shank as shown in Figure l7 ma com arise a tubular ortion havin P z:

a transverse plate 21 formed on the forward end thereof from which project forwardly a plurality of arms 22, 23, 24 and 25. Slid ably supported in the tubular portion of the shank is a body member 26 having a rearwardly extending portion 27 slidably fitted in the tubular portion of the shank as shown in Figure 4. The body member is provided with a longitudinal bore therethrough, the rearward end of the bore being suitably threaded to receive a set screw 28 against which a suitable compression spring 29 presses, the other end of the spring bearing against a slidable plug 30 fitted within the bore of the body member. The plug 30 is formed with a peripheral groove 31 into which an end of a set screw 32 projects, as shown in Figure 5, the screw 32 being threaded through the side wall of the tubular portion of the shank and passing loosely through an elongated slot 88 through the side wall of the extension 27 of the body member. The screw 32 thus anchors the plug 30 to the shank so that the spring 29 by pushing against the screw 28 tends to hold the body member in its limiting rearward position with respect to the shank, but at the same time a limited forward motion of the body member against the pressure of the spring 29 is possible. Between the intermediate portion of the body member 26 and its rearward extension 27 is a shoulder 34 which normally engages against the transverse portion 21 of the shank which limits its rearward movement. The body member 26 has an enlarged forward portion 35 which is rovided with a plurality of suitable radial slots 36 in its forward face to receive a corresponding number of thread-cutting chasers 37. Each chaser is splined in its groove as by a key 38, the chasers being also provided with springs 39 arranged to press them radially outward to their open position in which their cutting edges are sufiiciently separated from each other to clear the work. In order to move the chaser-s to their closed position for operatively engag ing the work and for holding them in closed position, a sleeve 40 may be provided having a forwardly extending flange 41 with an inner beveled face 42 adapted to engage complementary beveled faces 43 on the outer ends of the chasers 37. The sleeve 40 is permitted a sliding motion on the body member 26, limited by a suitable pin 44 extending radially through the wall of the sleeve 40 and having its inner end projecting into an elongated recess 45 formed in the body member 26. A suitable spring 46 may be provided to hold the end of the pin 44 in the recess 45. The length of the recess 45 limits the travel of the sleeve upon the body portion and it is preferably arranged to ermit the sleeve to move forwardly a su nt distance to close the chasers to their inwardmost position, and to move rearwardly sufiiciently to permit the chasers to move to their open position, but not to permit the forward end of the flange 41 to clear entirely the ends of the chasers 37 so as to permit the removal of the chaser-s from the body member. By retracting the pin 44 outwardly so as to clear the recess 45, however, the sleeve 40 may be moved further to the rear so as to permit the removal of the chaser-s from the die. The dieelosing motion of the sleeve 40 may be effected by any suitable means. As shown, the sleeve 40 is provided with a rack shaft 47 in which may be cut longitudinal recesses to form teeth 48 which mesh with a series of teeth 49 formed on the body member 26. The rack shaft 47 projects laterally from the sleeve 40 and may be provided with a suitable handle 50. By rotation of the rack shaft 47, the sleeve 40 may thus be advanced to die-closing position. In order to retain the sleeve in such position, a suitable latch 51 may be provided, this latch as shown in Fi ure 6 being preferably in the form of a ll crank rockably mounted on a pivot pin 52 which is carried by the sleeve 40. One arm of the bell crank latch 51 extends upwardly to form av trigger 53 which is pressed outwardly as by a spring 54 carried by the sleeve 40. The shorter arm 55 is adapted to catch in recesses cut in the side of a latch pin 56 which is connected to the body member 26 as by a screw 57. The latch pin 56 extends alongside of the intermediate portion of the body member 26 and is provided with a flange 58 which fits against the body member and prevents rotation of the latch pin. The recesses in the latch pin are thus always propel-l presented to the latch arm 55. The latc1 pin may be provided with three recesses 59, 60 and 61, the recess 59 being the deepest and furthest forward. \Vhen the die is in its open posit-ion, the latch arm 55 is ada ted to rest in the recess 60. Vhen the ie is closed, the latch 55 is adapted to rest in the recess 59 and to bear against a shoulder 62 between these two recesses, the shoulder 62 thus preventing rearward motion of the sleeve 40 with respect to the body member 26. The recess 61 receives the latch arm 55 when the pin 44 is retracted from the recess 45 and the sleeve is moved rearwardly to its position for allowing the removal of the chasers from the body member. In closing the die, the handle 50 is operated manually or by suitable mechanism to turn the rack shaft 47 so as to advance the sleeve 40 against suitable springs 63 which are carried between opposing faces of the body member and the sleeve, until the latch arm 55 drops into the recess 59 by the push of the spring 54 against the trigger 53. The shoulder 62 thereu on prevents retraction of the sleeve and t us holds the die in its closed position. The figures of the drawing illustrate the die in its open position. \Vhen in its closed position, a portion of the trigger 53 projects radially beyond the periphery of the sleeve 40. In order to open the die after a thread has been cut upon the work, the trigger 53 is pressed inwardly so as to release the latch 55 from the shoulder 62 and thus to permit the springs 63 to push the sleeve 40 rearwardly on the body 26. This in turn permits the springs 39 to push the chasers 37 radially outward to their open position. In order to trip the trigger 53 automatically, a tripscrew 65 is mounted in one of the forwardly extending arms 23 of the shank. The screw 65 is provided with an enlarged head having a beveled surface 66 ositioned in the path of the trigger 53. Vhen the thread on the work has been cut, the work then pulls both the body member and the sleeve forwardly against the pressure of the spring 29 so that the trigger 53 rides on the beveled surface 66 which forces itinwardly, releasing the latch 55 from the shoulder 62. The body member 27 and the sleeve 40 thereupon spring back independently but simultaneously to their rearward positions under pressure of the springs 29 and 63 respectively. The rearward. movement of ,the sleeve 40 relative 'to the body member 27 releases the chasers 37 for radial outward movement from the work under the influence of the springs 39, thus opening the die. The position of the bevel surface 66 may be adjusted forwardly or rearwardly by the screw and clamped as by a thumb nut 67.

Since the closed position ofthe chasers depends upon how, far forwardv the sleeve 40 moves with respect to the body member, the closed position of the chasers may be adjusted for diametrical size of the work by regulating the position at which the v sleeve is maintainedvby the latch 55 and the latch pin 56. Since the position of the shoulder 62 determines the position of the sleeve 40 with reference to the body member 26 when .the die is closed, the die may be adjusted for size byadjusting the $110111.- 7

der 62, that is, the latch pin 56, forwardly or rearwardly. To this end,the screw. 5. is .rotatablyheld in asuitable recess in the forward face of the body member 26, a set screw 68 being providedto hold the screw. 57 against longitudinal motion. It is apparent from Figure 5 that rotation of the screw 57 will result in a'longitudinal adjustment of the latch pin 56. V

The cutting pressure of the work on the chasers results in a considerable torque being impressed on the body portion, which torque must be carried by the shank which is held fixed in a turret orlathe. In order to provide a suitable bearing to transmit this torque from the body member to the shank, the former may beprovided with a pair of rollers 69 which are mounted to fit in spaces between, the arms 22 and 23 and between the arms 2% and 25; The rollers 69 may be securedto the body member 26 in any suitable manner. Asshown on the drawings, these rollers aremounted at the top and bottom of a driving plate 70 which asfshown in Figure-413 comprises a part of a circle having an eccentriccircular aperture 71 to receive the intermediate portion of the body 26. As shown, the rollers 69 are mounted with a common axis which is a diameter of the circle of, the plate 7 0 so that this common axis intersects the axis of the shank 20 and is perpendicular thereto. Extending laterallyfrom the aperture 71 in a direction perpendicular to the axis of the rollers 69 and t e axis of the shank 20 is a recess 72 having parallel-beveled edges 73, 7 Then the body member 26 is inserted through the aperture 71, it ,is moved laterally so thatthezbeveled ed es 7 3,7& slide respectively into notches 75, %6, cutin the intermediate portion of the body member. The plate 70 is thus non rotatably mounted on the body member after the sleeve 40 has been mounted thereon. Since the driving plate .7( isslidable in the grooves or notches 75, 76 in a direction perpendicular to the axis of the rollers 69, theplate can thus center itself so as to equalize the torsional thrusts on the two rollers 69, thus minimizing skew stresses between the body member and the fixed shank which otherwise would tend to spring the body member out of line.

In automatic turret machines, the turret is often indexed rapidly so that a closed die is sometimes prematurely opened by the indexing of the machine and thus is not in condition to operate upon work presented thereto. In order to prevent such premature opening of the die before the work is presented to it, means are provided according to the invention for locking the die in closed position until unlocked by the operative engagement of the work with the chasers 87. To this end, a lug 77 is mounted on the sleeve 4L0, this lug having a laterally extending projection 78 forming a shoulder 79 as shown in Figure 2. The arms 22 and .23 are likewise recessed respectively as at 80 and 81 forming shoulders 82 and 88. The lug 77 is, so hung as to lie between the arms 22 and 23 and a springpin 8% may be provided with a suitable spring85 by which the lug is pressed toward the left as shown in Figure 6, thus impressing a counterclockwise torque on the sleeve 40. As a result of this pressure, the projection 78 on the lug 77 is forced to bear against the edge of the arm 22 so that when the sleeve moves forwardly in order to close the die, the projection, 7 8 rides into the recess 80 and the shoulder 79 engages the shoulder 82, thus positively preventing further forward movement of the sleeve relative to the shank. This prevents accidental opening of the die prior to operative engagement with the work. When the work is brought up to engage the ohasers 37, the cutting resistance of the work tends to turn the body member and hence the sleeve in a clockwise direction if a right hand screw is being cut. This'moves the projection 78 out of the recess 80 and permits the work subsequently to pull the body member and sleeve forwardly to open the die when the cutting has been finished. If a left hand screw is cut, the lug 77 is turned over so that the projection 78 can enter the recess 81 and engage the shoulder 83 until released by engagement of work with the chasers. IVhen mounted for use, the die is preferably fixed in a lathe orin a turret of an automatic machine, the shank 20 being clamped to hold the die in fixed position. Before work is presented to the chasers, the die ,is closed by rocking the operating handle 50 either manually or by a suitable cam. This advances the sleeve 40 so that the projection 78 onthe lug 77 enters the recess 80 and the engagement of the shoulder 79 against the shoulder 82 prevents further iorward movement of the sleeve 40 which mightorprematurely open the die. When thaw is presented to the chasers, the rotation of the work and the cutting resistance 05' the'chasers turns the sleeve 40 throu a slight an le sufiicient to clear the shou der 79 from t e shoulder 82. When the thread has been cut on the work, the pull of thework upon the body member of the die moves t e body member with the sleeve 40 forwardly until the engagement of the trigger 53 with the trip pin cam surface 66 releases the latch 55 and opens the die. The chasers being freed from the work permit. the body member and sleeve to spring back to the normal open position illustrated on the drawin Havi n thus described certain embodimelts o this invention, it should be evident to those skilled in the art that various chan es and modifications might be made therein without departing from its spirit or scope as defined by the appended claims We claim I. In a screw-cutting die, a plurality oi chasers movable to open and closed positime, means for releasably holding the chasers inclosed: position, means actuable to release said die-closing means, and a locking mechanism for preventing the actuation of the releasing means, said locking mechanism being unlocked by operative engagement 0! the work with the chasers.

2. In a screw-cutting die, a plurality of Chasers movable to open and closed positions, a bed member in which said chasers are mount springs pressin the chasers toward their open osition, a s leeve movable on said body mem er, said sleevehaving a cam surface engageable with said chasers to move them against said sprin s to closed position when the sleeve is moved lorwardly on said body member, means for latchin said sleeve in its forward ition on sai body member to hold the c asers in closed position, means aotuable by further fiorward motion of said sleeve to release said' latchi-ng means, and means for positively looking said sleeve against said further forward motion, said locking means being unlocked by operative engagement of the work with saidehmers.

3: In a screw-cutting die, a fixed shank, a body member su ported by said shank and movable forwar ly relatively thereto, resi'lient means 0 posing forward motion. 0! said body mem er a plurality of chasers carried by said body member and movable toopen and closed positions, means for movi'ng' said chassis to closed osition comprising a sleeve slidable on saidbody member, p0

means for moving said sleeve forwardlyto close said die, means for latching said sleeve memes in its forward: position, means for releasing said latching means by forward movement of said; body member and sleeve relative to said shank, and means for preventing forward metinn oi'said body member, said preventing means being rendered in atiwe by operative engagement of the work with said c 4 n a screw-coming die, a fixed shank a: forwardly extending arm with a recess therein forming a shoulder, a hudy member supported by said shank for limited movement relative thereto, means for yiehlably maintaining said body membe:- at its limiting" rearward fposition relative tosaid slnlk, a plurality o Chasers carried by said body member and movable therein to open and closed positions, means for moving said chasers to closed position com rising a sleeve slidable forwardly on said dy member, means for latching said sleeve in its forward die-closing position means for re leasing said la means by further forward motion of sai sleeve with said bod member, and means for neventing sue further forward motion of the sleeve, said preventing means: comprising a l ng on said sleeve having a lateral pro'ection arran to enter the recess in said s ianli am an to age said shoulder and means tending to rotate the sleeve resiliently in a direction opposedto the rotation of the work to hold said projection in said recess until the ohas era are operatively engaged by the work.

5. In a screw-cnttin die, a body, a plurality of chasers carried by said body, a chaserengagin member movable forwardly relatively to said body to engage and retain said chasors in place and then to close said die, a latch pin adjustably secured to said body, said latch pin hwvinga stepped slot in the sidethereof formin a series of should'ers, and a latch mounte on saidmember to engage one of said shoulders when the die is closed, another of said shoulders when the die is open, and a third shoulder when said member is retracted suflieiently to permit removal of the ehasors from said bod 6\ In a screw cutting die, a fixed sha having'a fiorwardly projecting bod -receiving extension, a body member wit a said extension, a plurality of chasers carried by saidbudy member and movable to open and closed positions, a sleeve movable on said Body member to movesaid chaeers, and moans-carried by said body member for prenotatimr between said body member and said shank, said means comprising a driving plate nonwotatably mounted on said body member and transversely slidable thereon,- said plate having bearing elements at opposite e ges of sa i plate on a line nd'i'eular to the direction of slide 0! 'ng rtions of said shank rust o the torque impressed sai late 1 ta e'the g on the body member by the Work, the thrust on said elements being equalized by the freedom of motion of the plate in a direction perpendicular to the line of said elements.

In testimony whereof We have afiixed our signatures.

ERNEST T. BYSSHE. ROBERT R. FINN. 

